9.
The diagram below models the length from the center of a wind turbine to the tip of one of its blades.
Which of these is closest to the total area covered by the blade when the turbine makes1 revolution?
The total area covered by the blade when the turbine makes one revolution is a circle with a radius equal to the length from the center of the wind turbine to the tip of the blade. Therefore, the total area covered by the blade when the turbine makes one revolution is πr^2, where r is the length from the center of the wind turbine to the tip of the blade.
So, the total area covered by the blade when the turbine makes one revolution is closest to 3.14 times the square of the length from the center of the wind turbine to the tip of the blade.